Quantifying regional trends in large live tree and snag availability in support of forest management

In the Pacific Northwest of United States, 20th century timber harvesting resulted in major declines area forests supporting large live and dead trees (i.e., snags), that are not only key habitat elements for many wildlife species but also critical components ecosystem function. Regional forest management guidance, such as Forest Plan (1994) Eastside Screens (1995), may aim to conserve foster development late-successional old-growth forests, characterized by trees. Satellite remote sensing supports regional monitoring efforts these characteristics, managers require additional guidance order leverage data landscape or assessments. this study, our objectives were assess long-term (historical vs. contemporary) short-term (1993–2017) changes lands snags across 10 types (WHTs) – disparate vegetation conditions support significantly different communities Oregon Washington, USA. We generated 30-m, annual maps (>50 cm, >75 >100 cm diameter) (>25 > 50 based on gradient nearest neighbor (GNN) imputation method. GNN integrates Landsat satellite imagery, geospatial climatic topographic data, USDA Service Inventory Analysis predict attributes all forested study area. classification accuracy was poor good (Cohen’s kappa = 0.2 0.6) fair 0.1 0.3) most WHTs, though performance substantially lower drier WHTs where rare. Our results highlighted reductions from historical contemporary times, especially wetter, more productive WHTs. contrast, we observed increases areas snags. Federal both similar reference exhibited greater recent compared nonfederal lands. Thus, Washington have lost a substantial proportion containing recruitment at scales is slow process primarily occurring federal However, detecting through current mapping technologies remains challenging, highlighting need new methods aid future management.